Chromatography is a set of techniques for separating a mixture into its constituents. Well-established separation technologies include HPLC (High Performance Liquid Chromatography), UPLC (Ultra Performance Liquid Chromatography), and SFC (Supercritical Fluid Chromatography). HPLC systems use high pressure, ranging traditionally between 1,000 psi (pounds per square inch) to approximately 6,000 psi, to generate the flow required for liquid chromatography in packed columns. In contrast to HPLC, UPLC systems use columns with smaller particulate matter and higher pressures approaching 20,000 psi to deliver the mobile phase. SFC systems use highly compressible mobile phases, which typically employ carbon dioxide (CO2) as a principle component.
In general, in a liquid chromatography (LC) application, a solvent delivery system takes in and delivers a mixture of liquid solvents to an autosampler (also called an injection system or sample manager), where an injected sample awaits the arrival of this mobile phase. The mobile phase carries the sample through a separating column. In the column, the mixture of the sample and mobile phase divides into bands depending upon the interaction of the mixture with the stationary phase in the column. A detector identifies and quantifies these bands as they exit the column.
Tubing between equipment used in liquid chromatography, such as valves, pumps, and the column is typically made of stainless steel. Such material is readily available and capable of handling the elevated pressures and temperature range required for chromatography. Despite its hardiness, however, this material may corrode or erode at connection points to the detriment of the chromatographic results. The effects of the corrosion or erosion may include the loss of pressure or of flow, which affect retention times. Other negative effects may include carryover, and tailing and fronting of peaks.